With the continuous expansions of the scale of mobile communication network and the development of miniaturization of base stations, the number of network elements needed to be maintained by the operators is increasing rapidly, and the cost for maintenance is growing as well. To this end, a self-organization network (SON) mechanism is proposed which is intended to achieve a purpose of saving operating cost by realizing automation as much as possible in the phases of planning, deployment, operation and maintenance for the mobile communication network.
For the convenience of research and standardization on problems, the prior art defines a series of use cases for SON Standardization, and discusses corresponding solutions for each cases. Mobility Load Balance (MLB) is one of the solutions which is mainly used to solve the problem occurred in the course of automatically configuring and optimizing mobility-related parameters, the mobility-related parameters covers switching and cell reselection parameters. In terms of MLB, first, it is often important to precisely estimate information about the load of a cell, then exchange information by interfaces among the nodes, acquire information about the load of adjacent cells (also known as neighbor cells). Based on the load conditions of the adjacent cells along with certain algorithms and principles, the network modifies the parameters between the serving cell and respective adjacent cells, which may cause a terminal to reselect and switch to another cell. Thus, the load of the whole network will be more evenly distributed. Accordingly, the purpose of improving the capacity of a network, increasing the success rate for user access and reducing access delay will be achieved finally.
The existing MLB technology is mainly to migrate the users in an overloaded cell to an adjacent cell having a lighter load, which particularly can be realized by adjusting switching parameters. For instance, a virtual parameter Tc can be used to adjust cell selection performed by users as follows:
      X    ⁡          (      u      )        =      arg    ⁢                  ⁢                  max        c            ⁢                        P                      c            ⁢                                                  ⁢            •                          ⁢                                            L              c                        ⁡                          (                                                                    q                    →                                    u                                ,                                  Θ                  c                                            )                                ·                      T            c                              wherein X(μ) stands for the signal strength. It can be seen from the equation that the signal strength X(μ) turns weaker when the parameter Tc gets smaller, while the signal strength X(μ) turns stronger when the parameter Tc gets larger. Since the cell selection performed by a user is dependent on the signal strength, the parameter Tc of a certain cell can be reduced when the load of this cell is larger than a predetermined threshold value. As such, the user of this cell will select an adjacent cell when he performs cell reselection, thereby the load of this cell can be mitigated. In contrast, when the load of a certain cell is smaller than a predetermined threshold value, the parameter Tc of this cell will be increased. As such, users of adjacent cells will select this cell when they perform cell reselection, thereby more users may access to this cell.
In the course of research and practice of prior art, the inventor of the present disclosure discovers that when a plurality of users gather in some certain cells, though the call dropping rate/blocking rate can be reduced by forcing some users to switch to adjacent cells by means of adjusting switching parameters, spectral efficiency may correspondingly be reduced at the same time, especially when the user is relative far from the adjacent cell, the spectral efficiency is reduced more significantly, which may lead to a worse user experience.